Intro to Literate Programming by Howard Abrams possible errors

errors.txt

  - Too Many Parameters?
  
  error:  should "howard" should be in quotes?
  #+HEADER: :dir /etc
  #+HEADER: :var USER=howard
  #+BEGIN_SRC sh
    grep $USER passwd
  #+END_SRC
  
  - Language-Specific Default Values
  
    error: unecessary tilde.
    text: For Value enter: ~:dir /etc
    
  - Comments 
    clarification helpful:
    in #+PROPERTY: comments org
    what does the "org" do?
    
  - Footnote 1
  
    ".... _The_ originally saw each code block ...." ?
    
  - Noweb
  
    - broken link: Creates _last-col.sh_ source code that contains:
    - executing the 'ruby -ane' block
      1. "Code block produced no output."
      2. no file is created in the working directory
      
  - Reprocessing
  
    possible non sequitur (edit orphan?):
    "Once again, Ruby and Python being the close siblings that they are."
    
  - Cleaning Results
  
    not sure why the last line, ls -l is necessary.
    
  - Graphviz
  
    'd -> a;' should be 'c -> a;' to reproduce the graph.